Method of controlling volume in a noise adaptive manner and apparatus implementing thereof

ABSTRACT

A method for controlling volume in an apparatus having a speaker and a microphone includes receiving, at the microphone, external noise and speech of a user, and calculating sound pressure of the noise received by the microphone. The method further includes performing exception processing of the sound pressure of some or all of the noise using the calculated sound pressure and one of a speech utterance state, a speech receiving state, or a temporal length state, of the noise, mapping volume of the speech in response to the sound pressure of the external noise, synthesizing speech guidance into a sound file, outputting the sound file, via the speaker, according to the mapped volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Application No.10-2018-0022856, filed on Feb. 26, 2018, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND 1. Field of the Invention

The present invention relates to a method that controls volume in anoise adaptive manner and an apparatus for implementing such method.

2. Description of Related Art

There are various kinds of noise in the spaces where human and materialexchanges are made actively such as airports, schools, governmentoffices, hotels, offices and factories. Therefore, in the case of anapparatus such as a mobile guide robot that travels in theabove-mentioned space, it is required to operate in response to variouskinds of noise levels occurring in an individual zone.

For example, the contents of Korean Patent Application No.10-2008-0064557 are shown in FIG. 1, which depicts a method forimproving correctness of a speech signal according to the related art.FIG. 1 is related to analyzing a background noise signal of a receiverenvironment to classify a received speech signal into non-speech,unvoiced sound speech and voiced sound speech, and enhancing unvoicedsound speech or voiced sound speech classified based on the analyzednoise signal. In more detail, fast Fourier transform (FFT) is performedwith respect to the separated speech signal of the unvoiced sound speech(S1), and a signal to noise ratio (SNR) is calculated (S2).

Thereafter, according to the calculated result, the intensity of thespeech frame is compared with that of the noise frame (S3). When theintensity of the speech frame is greater than that of the noise frame,first calculation (S4) for adjusting the intensity of the speech frameis performed. When the intensity of the speech frame is less than thatof the noise frame, second calculation (S5) is performed. According tothe related art, the intensity gain (G) is set to 1 for the firstoperation and a root operation is performed for the noise signal withrespect to an intensity gain for the second calculation.

When the related art as shown in FIG. 1 is applied, as the volume isadjusted in real time, the volume continuously fluctuates during theoutput of speech, which may interfere with the recognition of the userwith respect to the speech. In particular, even when accidental loudnoise is generated, there is a problem that the volume is unnecessarilyincreased as an intensity of the noise is continuously measured.

As an example, embodiments described in the present specificationprovide a method that a device having mobility adjusts the volume tocope with a state where noise is generated and a state where the volumeis controlled, to enable a user to effectively recognize the speech.

SUMMARY

Embodiments described in the present specification may be used to solvethe above-mentioned problems. An embodiment includes a method in whichan apparatus that provides a user with information through sound or TTSspeech outputs the speech in an adaptive manner to ambient noise so asto enhance a recognition rate of the user with respect to the speech.

A further embodiment provides a method of fixing volume of an apparatusor reducing a range of changing volume of an apparatus in a process inwhich the apparatus that provides the user with the information throughthe sound or the TTS speech outputs the speech in an adaptive mannerwith respect to the noise generated temporarily from the ambient and theusers recognize the sound.

A still further embodiment provides a method of controlling the outputvolume in response to the temporal and sound pressure characteristics ofthe noise generated during the movement of the apparatus.

According to an embodiment, a volume control apparatus includes anexception processing unit that instructs exception processing duringcalculation of sound pressure of noise in consideration of a speechutterance state, a speech receiving state, or a temporal length state ofnoise.

According to an embodiment, the volume control apparatus includes ascenario engine unit that provides information on the speech utterancestate, the speech receiving state, or the temporal length state ofnoise.

According to another embodiment, the volume control apparatus mapsvolume of the uttered speech as a first slope in response to an increasein the sound pressure of the noise and maps the volume of the utteredspeech as a second slope in response to a decrease in the sound pressureof the noise, and the absolute value of the first slope is smaller thanthe absolute value of the second slope.

According to an embodiment, the robot includes a volume control modulethat instructs exception processing during the calculation of soundpressure of noise in consideration of a speech utterance state, a speechreceiving state, or a temporal length state of noise, and a map storageunit that stores noise information on a space where a robot travels.

According to an embodiment, the robot includes a control unit thatcontrols the sound pressure of the noise calculated by the volumecontrol module to be collectively stored as noise information in the mapstorage unit with respect to the position information of the receivednoise. When the deviation of the noise information stored with respectto the position information on the map storage unit is equal to or lessthan a predetermined level, and the robot moves to the position, thevolume control module maps the volume in response to the average valueof the stored noise information.

According to an embodiment, a method for controlling a volume in a noiseadaptive manner includes exceptional processing sound pressure of a partor all of the noise in consideration of a speech utterance state, aspeech receiving state, or a temporal length state of the noise, mappingthe volume of the uttered speech in response to the calculated soundpressure of the noise, and controlling the speaker unit to output thesound file to the mapped volume.

Various embodiments may be applied by providing a user with informationthrough the sound or the TTS speech, the exception processing isperformed during the calculation of the sound pressure with respect tonoise in consideration of the speech utterance state, the speechreceiving state, or the temporal length state of noise. Thus, it ispossible to output the speech in a noise adaptive manner with respect tothe ambient noise.

Various embodiments include the output volume being fixed or the rangeof changing the output volume can be narrowed during a certain unit oftime or unit output to increase the speech recognition rate of the userwith respect to the temporal and sound pressure characteristics ofnoise.

Various embodiments make possible to provide information on a speechutterance state, a speech receiving state, or a temporal length state ofa noise, so that the measurement of the noise and the operation thereofcan be embodied differently depending on the utterance state of theapparatus or the robot.

These and other embodiments will also become readily apparent to thoseskilled in the art from the following detailed description of theembodiments having reference to the attached figures, the invention notbeing limited to any particular embodiment disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a method for improving correctness of a speech signalaccording to the related art.

FIG. 2 shows a configuration of a volume control apparatus according toan embodiment of the present invention.

FIG. 3 shows a process in which a volume control apparatus operatesaccording to an embodiment of the present invention.

FIG. 4 shows a sigmoid function applied when mapping between noise SPLand speech guidance SPL is made according to an embodiment of thepresent invention.

FIG. 5 shows a configuration of a robot 200 according to an embodimentof the present invention.

FIG. 6 shows an interaction between components according to anembodiment of the present invention.

FIG. 7 shows a process in which an exception processing unit instructsexception processing of a sound pressure level of noise according to anembodiment of the present invention.

FIG. 8 shows a process in which a volume conversion unit converts volumeaccording to an embodiment of the present invention.

FIG. 9 shows a process of storing sound pressure of noise generated ineach space obtained during the movement of the robot for each positionand using the stored sound pressure of noise according to an embodimentof the present invention.

FIG. 10 shows a sound pressure of noise stored in a map storage unitaccording to an embodiment of the present invention.

FIG. 11 is a view of timing at which a calculation of sound pressure isperformed according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings so that those skilled in the artto which this application pertains can easily embody the presentinvention. The present invention may be embodied in various differentmanners and is not limited to the embodiment described herein.

In order to clearly illustrate the present invention, a part that is notrelated to the description may be omitted, and same or similarcomponents are denoted by a same reference numeral throughout thespecification. Further, some embodiments in the present invention willbe described in detail with reference to exemplary drawings. In addingreference numerals to components of each drawing, the same componentsmay have the same reference numeral even if they are displayed ondifferent drawings. Further, in the description of the presentinvention, a detailed description of related known configurations andfunctions will be omitted when it is determined that it may obscure thegist of the present invention.

In the description of components of the present invention, it ispossible to use the terms such as the first, the second, A, B, (a), and(b), and the like. These terms are only intended to distinguish acomponent from another component, and a nature, an order, a sequence, orthe number of components, are not limited by that term. When a componentis described as being “connected”, “coupled”, or “connected” to anothercomponent, the component may be directly connected or able to beconnected to other component; however, it is also to be understood thatadditional component is “interposed” between the two components, or thetwo components may be “connected”, “coupled”, or “connected” through anadditional component.

Further, with respect to implementation of the present invention, forconvenience of explanation, the invention will be described bysubdividing an individual component; however, these components of theinvention may be implemented within an apparatus or a module, or acomponent of the invention may be implemented by being divided into aplurality of apparatuses or modules.

Hereinafter, an apparatus that controls a volume (or a volume controlapparatus) may be made solely or may be coupled integrally with a robothaving mobility. The robot moves according to an external control orautonomously moves based on information such as a map and provides apredetermined function.

Therefore, the robot includes all the apparatuses that have a specificpurpose (cleaning, security, monitoring, guidance, and the like) orprovide functions according to the characteristics of a space where therobot moves and moves by the autonomous or external control. Further,the robot is collectively referred to as an apparatus that has a movingmeans capable of moving by using predetermined information and a sensor,and provides a predetermined function.

Sound pressure level (SPL) refers to the pressure of sound, that is, thelevel of sound pressure. When the noise is loud, the sensed soundpressure increases. When the noise is small, the sensed sound pressuredecreases.

FIG. 2 shows a configuration of a volume control apparatus according toan embodiment of the present invention. The volume control apparatus 100includes a microphone unit 110, a noise sound pressure calculation unit(a noise SPL calculation unit) 120, an exception processing unit (SPLcalculation rejection control unit) 130, a volume conversion unit(SPL-to-volume mapper) 140, a scenario engine unit (UI scenario engine)150, a sound synthesis unit (TTS player) 160, a volume control unit 170,and a speaker unit 180. Each of these components will now be described.

For example, the microphone unit 110 is provided for speech recognition,and is generally open to supply a received acoustic signal to a system.Noise generated from the outside and speech that a user utters isinputted to the microphone unit 110. The microphone unit 110 picks upexternal noise and voice of a user. During the input of the noise andthe speech, the microphone unit 110 may set a specific sampling ratesuch as mono/16 kHz/16 bit during sampling. Alternatively, the samplingrate of the microphone unit 110 may be set differently according to theambient noise.

The noise sound pressure calculation unit 120 calculates sound pressureof noise inputted to the microphone unit 110. The SPL of the noise, thatis, the sound pressure is calculated by using the inputted noise signal.The increase in the SPL value is slowly controlled and the decrease inthe SPL value is rapidly controlled. This will be described in moredetail below.

The exception processing unit 130 instructs the exception processing ofthe sound pressure of some or all of the noise by using the resultcalculated by the noise sound pressure calculation unit 120, that is,the calculated result, in consideration of the speech utterance state,the speech receiving state, or the temporal length state of the noise. Astate of uttering speech refers to a state where the volume controlapparatus 100 utters a predetermined guide phrase and the speaker unit180 outputs the uttered predetermined guide phrase. A state of receivingspeech means a state where a user inputs a command or other soundthrough speech. A state of the temporal length of noise means magnitudeof noise and with a state of time duration. It is possible to increasethe volume of the sound outputted by the speaker unit 180 in response tosuch noise if a certain level of noise continues. On the other hand, ifthe noise of a very short temporal length is inputted for a time period,the noise can be exceptionally processed and the volume of the speechoutputted by the speaker unit 180 can be controlled so that it is notincreased.

A further state is where temporary loud noise may be input, or a speechcommand of a user or a speech guidance of the robot may be detected tostop SPL calculation or to calculate the sound pressure for the receivedloud sound can be exceptionally processed. Further, the exceptionprocessing unit 130 can detect the state information based on a userinterface (UI).

The volume conversion unit 140 maps the volume of the uttered speech inresponse to the sound pressure of the noise calculated by the noisesound pressure calculation unit 120 and the exception processing unit130. The volume conversion unit 140 maps appropriate volume for the SPLof the noise and converts the mapped appropriate volume. Further, thevolume conversion can be stopped during output of the speech guidance.Further, it is possible to sense the output of the guided speech.

The scenario engine unit 150 is a component that controls a UI scenario,and controls the UI. The scenario engine unit 150 provides the exceptionprocessing unit 130 with information on the speech utterance state, thespeech receiving state, or the temporal length state of the noise. Inthis process, the speech guidance is outputted and the state ofrecognizing the speech of the user can be shared with other components.

The sound synthesizing unit 160 synthesizes information on the speechguidance sentence to be outputted by the volume control unit 100 intosound (for example, PCM sound), and the sound control unit 170 adjusts amagnitude of the sound guidance signal to be the numerical value of thetarget volume. The speech synthesizing unit 160 synthesizes the speechguidance sentence into a sound file of a predetermined format, and thesound file may be stored in advance with respect to the guide sentence,or may be generated in real time. The volume control unit 170 controlsthe sound file to be outputted to the volume mapped by the speaker unit180.

The speaker unit 180 amplifies a speech guidance signal and outputs theamplified speech guidance signal. The speaker unit 180 may reflect anamplification factor during the calibration of a mapping functionrelated to an amplification output.

When the volume control apparatus 100 shown in FIG. 2 or a robot orother device equipped with such a control apparatus, guides while movingin an airport, a hotel, a shopping mall, and the like, it is possible toprovide the speech guidance of the appropriate volume that can berecognized by a user with respect to a different level of ambient noiseeverywhere in a moving path within the service area.

The microphone unit 110 of the volume control device 100 measures thelevel of the ambient noise. Each component of the volume controlapparatus 100 obtains a minimum utterance magnitude of the speechguidance and determines the output volume based on logic for measuringonly background noise except for a sudden loud noise or speech guidanceof the product itself.

Further, the sound pressure conversion unit 140 maps the output volumefor each the level of the ambient noise approaching the limits. Further,the speech synthesizing unit 160 and the speaker unit 180 and the likemay stop the volume control during the output of the speech for ensuringthe recognition of the speech guidance of the user and it is possible toprevent the output volume from being suddenly increased during theutterance of the volume control apparatus 100 or the robot.

FIG. 3 shows a process in which a volume control apparatus operatesaccording to an embodiment of the present invention.

A noise sound pressure calculation unit 120 of a volume controlapparatus 100 measures a SPL of ambient noise by using a signal inputtedto the microphone unit 110 (S10). For example, an A-weight filter isapplied to the signal inputted to the microphone, which is included inthe volume control apparatus 100 to calculate the SPL in a dB unit.

An exception processing unit 130 performs exception processing forsounds that are not background noise (S11). For example, the exceptionprocessing unit 130 may set the background noise to the lowest valueamong the SPLs to be measured. When a sudden loud sound is inputted tothe microphone unit 110 or speech is inputted for a speech recognitioncommand of the user, calculation of background noise may be stopped toeliminate unnecessary errors.

In the calculation of the SPL, the increase in the value is madesmoothly and the decrease in the value is made significantly, maximizinga tendency to stay at the lowest value. When the ambient noise maintainsa certain level and suddenly becomes large, exception processing isperformed to gradually increase the volume of the speech guidance. Forexample, when the ambient noise suddenly increases and then suddenlydecreases again, it is rapidly returned to the volume of original speechguidance.

The volume conversion unit 140 maps the volume based on the noise SPLand the speech guidance SPL. For example, a sigmoid function can be usedas shown in FIG. 4. The volume conversion unit 140 can nonlinearlychange the volume of the correct speech guidance expected by the useraccording to the level of the ambient noise. Such a change can beexpressed as the sigmoid function of FIG. 4. In this process, an optimumparameter can be applied by calibrating the position where the volumecontrol device 100 utters and the position where the noise is generated.

Then, in a state where sound is outputted through a speaker unit 180, avolume control depending on external noise is stopped (S13). Thefunction for controlling the volume depending on the external noise ofthe components of the volume control apparatus 100 is interrupted for awhile in the state where the speech is outputted, thereby preventing thevolume from being suddenly changed due to the external noise.

The volume control apparatus 100 senses a state of the speech output andtemporarily stops the volume control and the volume is not changedduring reproduction of the speech guidance, thereby preventing therecognition of the user from being degraded. Therefore, the volume whichis controlled at the starting point of outputting a guide speechsentence is maintained until an utterance of the guide speech sentenceis ended.

FIG. 4 shows a sigmoid function applied when a mapping between a noiseSPL and a speech guidance SPL is made according to an embodiment of thepresent invention.

In view of the sigmoid function of FIG. 4, when the noise SPL is acertain level (for example, 30 dB or less), the increase in the SPL ofthe speech guidance is gradually made. For a noise SPL of a certainrange (for example, 30 dB to 70 dB), the increase in the SPL of thespeech guidance is steeply made. Further, when the noise SPL is acertain level (for example, 70 dB or more), the increase in the SPL ofthe speech guidance is smoothly made.

In summary, as shown in FIG. 4, the SPL of the noise is divided into twoor more sections. In a first section, a slope of speech guidance SPL tothe noise SPL may be smoothly increased. In a second section, a slope ofspeech guidance SPL to the noise SPL may be steeply, increased.

As shown in FIGS. 2 to 4, the volume control apparatus 100 or a robotequipped with such an apparatus senses the correct noise SPL inputted tothe microphone unit 110, thereby minimizing an influence of sound otherthan background noise. As a result, it is possible to meet expectedvolume of the speech guidance from a viewpoint of a customer and preventan unnecessary change of volume from being generated during listening ofthe speech guidance.

In particular, the volume control apparatus 100 or the robot equippedwith the volume control apparatus 100 can determine an exception statebased on a certain unit (one or more sentences, a word, and the like)during the utterance of the speech guidance. Accordingly, during thespeech guidance of one unit, the volume control device 100 may determinethe current state as an exception state, and stop the control forincreasing volume of the guidance speech with regard to the ambientnoise.

Further, when a time point at which the speech guidance starts (at atime point of utterance) is stored in the volume control apparatus 100or the robot equipped with the volume control apparatus 100 or ispredicted therefrom, the function for changing the volume of the utteredspeech in response to the SPL of the ambient noise based on the timeinformation can be on/off.

As shown in FIGS. 2 to 4, the volume control apparatus 100 may bemounted on the robot as a module. In the case of a mobile robot, thevolume control apparatus 100 may control the output volume in anadaptive manner to external noise to improve the recognition ratio ofthe speech guidance.

As a result, it is possible to solve the problem in which the usercannot confirm the contents of the speech guidance as the volume of therobot is suddenly increased by controlling the speech guidance to thevolume suitable for the user to be recognized in response to the levelof the ambient noise which varies according to the position of themobile robot. Of course, such embodiments are not necessarily applied toa mobile robot, and may be applied to a case where a command of the useris inputted when the robot is fixed. In addition, various embodimentsare discussed with reference to a robot, but such teachings applysimilarly to other devices and systems.

FIG. 5 shows a robot 200 according to an embodiment of the presentinvention. In the robot of FIG. 5, the volume control apparatus shown inFIG. 2 is mounted in a volume control module 100 a.

The configuration and the operation of the volume control module 100 aare generally the same as shown in FIGS. 2 to 4.

A map storage unit 210 stores noise information of a space that a robottravels. It is possible to store the magnitude of the noise received ata specific location or at a specific time in the location. The suddenlyincreased noise can be excluded.

A communication unit 220 is a component for a robot 200 to exchangeinformation with another robot or a server.

A moving unit 230 is a component that moves a robot and includes varioustypes of mechanical components that move the robot such as a wheel or acaterpillar.

An operation unit 240 performs a specific function set in the robot.Specific functions include various functions such as cleaning, security,guidance, and baggage delivery, and the like.

A control unit 250 controls a volume control module 100 a, a map storageunit 210, a moving unit 230, and an operation unit 240.

An interface unit 290 may be selectively included in the robot, and aspeaker unit 180 of the volume control module 100 a may be arranged inthe interface unit 290 to output sounds to the outside. Alternatively, adisplay unit that outputs visual information such as characters or lightmay be arranged in the interface unit 290.

The speech guidance is controlled at appropriate volume suitable forbeing recognized with respect to the level of the ambient noise thatvaries for each position that the robot 200 moves, and therebyrecognition rate of the speech guidance of the user may be increased.For example, the volume control module 100 a may stop the backgroundnoise calculation when sudden loud sound is inputted during themeasurement of the background noise, or when speech for the command ofthe user with respect to the speech recognition is inputted. In themeasurement of background noise, the increase in the value can be madesmoothly, and the decrease in the value can be made significantly so asto gradually match the increase of the noise.

Further, it is possible to nonlinearly map the magnitude of volume ofthe speech guidance to the level of the background noise. For example,the sigmoid function of FIG. 4 can be applied. During the reproductionof the speech guidance, the volume control is temporarily stopped tosolve a problem that the sound of the speech guidance suddenly increasesdue to the sudden noise.

The speech guidance volume is set to the lowest energy based on thebackground noise that is inputted, thereby being suitable for tracking.The volume control of the volume is performed in a minimum unit, forexample, a sentence unit, so that the volume up does not occur suddenly.The volume can be adjusted for each sentence unit, or if there is acertain speech pause period in the sentence the case of a compositesentence), the volume can be adjusted based on the speech pause period.

FIG. 6 shows an interaction between the components according to anembodiment of the present invention. It will be described with referenceto FIGS. 2 and 5.

Noise is inputted to a microphone unit 110 from an outside and themicrophone unit 110 provides a noise sound pressure calculation unit 120with the inputted noise (S21 a, S21 b). In this process, before themicrophone unit 110 provides the noise sound pressure calculation unit120 with the noise, the noise is provided to a preprocessing unit 115(S21 a), and the preprocessing unit 115 may apply a correction filterfor precise calculation of the sound pressure of the noise to providethe noise sound pressure calculation unit 120 with the corrected noise(S21 b).

The preprocessing unit 115 compensates the frequency characteristic of amicrophone so that the sound pressure can be precisely measured. Forexample, background noise is only selected by analyzing a microphonesignal and the SPL is precisely calculated in a dB unit. Further, it ispossible to precisely measure the sound pressure by compensating thefrequency band of the inputted microphone with an A-weight frequencyresponse curve method.

The noise sound pressure calculation unit 120 performs the signalprocessing with respect to the result that the preprocessing unit 115corrects to calculate the SPL of the noise level.

The noise sound pressure calculation unit 120 precisely calculates theSPL of the noise level through the signal processing. For example, thelevel of the signal can be confirmed by using an analog VU meter (volumeunit). An audio input can be rectified by using a diode and a capacitorcan be used to adjust a rising/falling time to display power of thevoltage rectified on a VU meter as a log-scale (log₁₀(x²)). The SPL ofthe noise can be calculated by using the log scale shown. In thisprocess, the sound pressure of the noise of a meaningful range (dB) maybe extracted, and the noise sound pressure calculation unit 120determines the extracted sound pressure of the noise as the soundpressure of the noise.

Meanwhile, during the calculation of the noise through the noise soundpressure calculation unit 120, an exception processing unit 130 caninstruct the exception processing with respect to the sound other thanthe background noise (S23). With respect to the information required forthe exception processing unit 130 to instruct the exception processing,a scenario engine unit 150 can provide state information to theexception processing unit 130.

The state information provided by the scenario engine unit 150 to theexception processing unit 130 may be a speech utterance state (TTSactive state), a speech receiving state (VR active state and KA resultstate). The speech utterance state refers to a state where the robotutters a guide phrase through text to speech (TTS) or outputs previouslystored sound.

Two states of receiving speech may be provided. The KA result state(keyword activation result state) means a state where a start-up word isinputted to notify that the user inputs a predetermined command to therobot or the volume control apparatus. When the start-up word isinputted, it is in a state of waiting for the speech input. VR activestate (voice record state or voice recognition state) means a statewhere speech of the user is inputted.

The scenario engine unit 150 notifies the exception processing unit 130of a state of the current utterance or a state where it waits for thespeech input or the speech is inputted (S23). Further, when the temporallength of the inputted noise is equal to or lower than a predeterminedlevel, the exception processing unit 130 may instruct the noise soundpressure calculation unit 120 to perform the exception processing duringcalculation of noise sound pressure with respect to instantaneous noise(S23).

The noise sound pressure calculation unit 120 calculates the SPL (soundpressure level) of the noise calculated by the scenario engine unit 150and the exception processing unit 150 in a dB unit and provides thecalculated SPL to the volume conversion unit 140 (S25). Further, in thisprocess, the scenario engine unit 150 may provide the volume conversionunit 140 with information on a current utterance state of an apparatusor a robot or a message to be uttered (S26).

In more detail, in S26, it is possible to indicate whether sound to beoutputted is a TTS event message or a file play event message thatreproduces a previously stored file. Accordingly, the volume can becalculated differently.

A volume conversion unit 140 sets the volume of a guide phrase to beoutputted by using a level of the sound pressure of the noise and theinformation on the current state provided by a scenario engine unit 150.As described above, the volume suitable for the current noise level canbe calculated by calibrating a SPL value that a robot utters by thesigmoid function as shown in FIG. 4, which is expected according to thesound pressure level (SPL) of the background noise.

On the other hand, a speech synthesizing unit 160 also converts a guidephrase provided by the scenario engine unit 150 into a speech file(S27). The generated speech file (TTS file), for example, a PCM file isprovided to a volume control unit 170 (S28), and the volume conversionunit 140 provides the set volume to the volume control unit 170 (S29).As a result, the volume control unit 170 provides the sound file to beoutputted and the volume set by using the information provided in S28and S29 to the speaker unit 180, and the speaker unit 180 outputs thesound file.

The volume control unit 170 may set the volume to the calculated volumevalue for the file play event message and perform post-processing toimprove the correctness of the speech with respect to the TTS eventmessage. Depending on the type of sound to be outputted, with respect tothe TTS, the post-processing can be performed so that the user cancorrectly recognize the speech. On the other hand, in the file playevent message that is the reproduction of the stored sound file, thesystem volume can be set according to the sound pressure level of thenoise.

Based on the configuration and the process of FIG. 6, the volume controlapparatus or the robot equipped with the volume control apparatuscontinuously measures the noise and exceptionally process the noisemeasurement in an exception state (such as when a robot utters orreproduces specific sound, or it waits for speech input of a user or thespeech is inputted).

The exception processing can be made with respect to loud noisegenerated in a short period of time (for example, short and loud noiseswithin 2 seconds). When the sound pressure of the noise is calculated, asmall weight is set, and an importance with respect to the short andloud noise can be set lower in the calculation of the sound pressure ofthe noise.

FIG. 7 shows a process in which an exception processing unit instructsexception processing of a sound pressure level of noise according to anembodiment of the present invention. According to FIG. 7, the processperforms the exception processing with respect to sound other thanbackground noise. For example, an exception state of estimating noise isan utterance of a robot, a speech command, and loud sound in a shortinterval.

An exception processing unit 130 receives state information from ascenario engine unit 150 (S41). The state information may be a statewhere an apparatus or a robot utters (speech guidance, notificationsound, escort music), a speech command (keyword recognition, and speechof the customer during speech recognition).

The exception processing unit 130 identifies whether a current state isin an exception state (S42), and sets a flag to stop the estimation ofthe background noise (S43). This flag instructs the noise sound pressurecalculation unit 120 not to calculate the sound pressure for thebackground noise.

The scenario engine unit 150 identifies whether the robot is in anutterance state (a state where TTS is outputted or particular sound fileis reproduced) or the robot is in a state of receiving the speechcommand (keyword activation, voice recognition) and transmits the stateinformation to the exception processing unit 130.

Thereafter, the exception processing unit 130 continuously identifiesthe state during the certain period (for example, a short period, forexample, 0.2 seconds and 0.3 seconds) to monitor whether the exceptionstate is generated or such a state is resolved. If a value of a flag isadjusted so that a noise sound pressure calculation unit 120 refers, thenoise sound pressure calculation unit 120 may calculate or not calculatethe sound pressure for the background noise according to the change ofthe flag value.

In the case of a speech utterance state and text to speech (TTS) output,the exception processing unit 130 may instruct the exception processingon the basis of a minimum unit of a notice to be uttered. The minimumunit can be a sentence. Therefore, the exception processing is madewhile a sentence is outputted through speech, and the sound pressure ofthe background noise can be measured when there is a time intervalbefore the next sentence is outputted. At a time point at which the nextsentence is outputted, the sound pressure of the background noise can bemeasured by making the exception processing again.

In this case, even when loud sound is generated during the output of onesentence through speech, it is possible to output sound at constantvolume so that the volume is not changed.

The exception processing unit 130 may instruct the exception processingduring a time of waiting for the speech utterance when a start-up wordis inputted to the microphone unit 100. When a start-up word (keyword)is inputted, the user can make a speech command thereafter, so that theprocessing of the background noise can be stopped.

Refining logic is applied after processing an exception state (S44). Forexample, it is a counter based logic for rejecting an influence of anonset at the beginning of a loud speech in a short interval or keywordrecognition.

The exception processing unit 130 additionally manages the preset levelsound pressure value. When an instantaneously measured sound pressure(an instantaneously measured SPL) is greater than a preset level soundpressure (S45), the noise SPL is increased to the first scale (S46). Onthe other hand, when the instantaneously measured sound pressure(instantaneous measurement SPL) is smaller than the preset level soundpressure (S45), the noise SPL is reduced to a second scale (S47). Theabsolute value of the first scale is smaller than that of the secondscale. For example, the first scale is 0.0005 dB and the second scale is0.01 dB. The absolute value of the second scale can be set greater thanthat of the first scale.

In S46 and S47, in the application of the SPL value of the measurednoise to the SPL of the background noise, an onset process for theincrease is slowed down and the offset process for the decrease isaccelerated to calculate the SPL only for the actual background noise.

Further, the exception processing is performed according to the durationof noise (S48). The noise generated for a short period of time can beexcluded in the calculation of the sound pressure of the backgroundnoise, thereby it is possible to prevent the output volume of the robotfrom being excessively increased. With respect to the loud sound orvoice in the short interval, the time can be measured by using a delaytime counter in order to stop the influence on the onset for theapplication to the noise SPL or reduce such an influence, or remove suchan influence.

For example, when an SPL measurement value of noise exceeding a presetlevel of sound pressure by a predetermined magnitude (for example, 6 dB)is confirmed, the duration of the noise is counted in a sample unit of 2seconds in a state where a rate of reflecting onset is slowed down to a0.00002 dB. When the measurement value of the SPL exceeding the level ofthe sound pressure by a predetermined magnitude (for example, 6 dB), thereflection rate of the onset is set to 6 dB and the level of the soundpressure can be increased to the measured SPL level.

In summary, the noise that lasts a certain reference time (for example,2 seconds) or less by counting the duration of the noise is excluded inthe calculation of the sound pressure of the background noise or thenoise that lasts a certain reference time (for example, 2 seconds) orless is reduced to very small magnitude and calculated. On the otherhand, for the noise that lasts a certain period of time or more, thesound pressure of the background noise is calculated and the soundpressure of the level of the noise can be increased by predicting thatsuch noise continuously lasts.

By an example of FIG. 7 being applied, the exception processing may beperformed so that e sound pressure of the noise inputted to themicrophone unit 110 may not be calculated at all, or the sound pressureof the sound may be calculated by reducing to the preset ratio. Forexample, when the measured sound pressure of the noise is large asexemplified in S44 to S48 according to the refining logic, the soundpressure of the noise is increased by a small unit (S46). If the noiseis reduced, the sound pressure of the noise is decreased by a large unit(S47).

FIG. 8 shows a process in which a volume conversion unit converts volumeaccording to an embodiment of the present invention.

A volume conversion unit 140 receives the sound pressure of the noisefrom a noise sound pressure calculation unit 120 (S51). Then, it isidentified whether the sound pressure of the noise is increased or not(S52). In response to the increase in the sound pressure of the noise,volume of the uttered sound is mapped as a first slope (S53). If thesound pressure of the noise is not increased, the volume of the utteredspeech is mapped as a second slope in response to the decrease in thesound pressure of the noise (S54). The absolute value of the first slopeis set to be smaller than that of the second slope. For example, even ifthe sound pressure of the noise increases, the volume of the utteredspeech is mapped with a small increase rate (the first slope). When thesound pressure of the noise decreases, the volume of the uttered speechis mapped with a larger decrease rate (the second slope). The mappedvolume is provided to the volume provision unit 170, and the robotoutputs speech or media files with the controlled volume.

Alternatively, even when the noise of S53 is increased, the volume canbe mapped differently. For example, by applying the sigmoid function ofFIG. 4, the sound pressure section of the noise can be divided intothree sections, which is set sequentially from the smallest soundpressure section, for example, a first section (for example, 30 dB), asecond section (for example, 30 dB to 70 dB), and a third section (forexample, 70 dB). The sound pressure of the second section is larger thanthe sound pressure of the first section, and the sound pressure of thethird section is larger than the sound pressure of the second section.

The volume conversion unit 140 maps the volume to increase as the firstslope in response to the sound pressure of the sound calculated when thecalculated sound pressure of noise belongs to the first section, andmaps the volume to be increased as the second slope in response to thecalculated sound pressure of the noise when the calculated soundpressure of the noise belongs to the second section, and maps the volumeto be increased in the third slope in response to the calculated soundpressure of the noise when the calculated sound pressure of the noisebelongs to the third section.

The second slope has a value larger than the first slope and the thirdslope. For example, the volume conversion unit 140 maps the volume as aslow slope (that is, with a small increasing rate) with respect to thesound pressure of the noise in the first section and the third section,and maps the volume in the steep slope (that is, with a large increasingrate) with respect to the sound pressure of the noise in the secondsection. As described above, when the sound pressure of the noise isdivided into two or more sections and different increase ratios(different slopes) are applied, respectively, the system volume iscontrolled to be suitable for the measured background noise SPL so thatthe speech or the type of the reproducing file can be recognized fromthe viewpoint of a user. For example, a proportion for each section isapplied to the volume magnitude of the speech guidance expected for eachsound pressure section of the noise, instead of a constant proportion.

Of course, the sound pressure of the noise can be divided into twosections, instead of three sections. The volume may be mapped so as toincrease with a small magnitude in the first section (small soundpressure band) and the volume may be mapped so as to increase with alarge magnitude in the second section (large sound pressure band).

In summary, the volume conversion unit 140 can apply the sigmoidfunction when the volume to be mapped is calculated in response to thesound pressure of the noise.

The volume conversion unit 140 may use the above-mentioned sigmoidfunction FIG. 4 in the mapping of the volume in response to the noise,and may use Equation 1 that embodies the above.

$\begin{matrix}{L_{TTS} = {{{Var}\;{1 \cdot \frac{1}{{{Var}\; 5} + e^{{Var}\;{3 \cdot {({L_{Noise} + {{Var}\; 4}})}}}}}} + {{Var}\; 2}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, Var1 is selected in accordance with the gain value of theoutput speech with respect to the sound pressure of the inputted noise.Var2 means an absolute volume, i.e., a value of level of volume of guidespeech that has to be obtained.

Var3 is a curvature of a sigmoid function and Var4 is a variable forcompensating an output during measurement of external noise. Forexample, when Var1 is a positive number, Var3 is a negative number. Var5is also a variable required when the sound pressure of the noise and thevolume of the TTS speech are mapped in the implementation of the sigmoidfunction.

The various variables of Equation 1 can be variously selected accordingto the environment where the robot or the volume control apparatusoperates, or the type of speech guidance to be outputted, and the like.

When Equation 1 is applied, with respect to the system volume, the SPLof the noise can be measured in a specific unit (for example, 1% unit)and a logarithmic function can be set. Then, an inverse function can becalculated and the target volume V for the required SPL of the TTSspeech can be set as shown in Equation 2.V=10^((L) ^(TTS) ^(+Var6)/Var7)(%)  Equation 2:

According to another embodiment of the present invention, the robotequipped with a volume control module 100 a stores the sound pressure ofthe noise in the map storage unit, and when the level of the soundpressure is constant, it corresponds to the sound pressure of the noiseat the position. For example, the entire space can be divided into cellsof a certain size (for example, 1 m of width and 1 in of height), andthe sound pressure of the background noise measured for each of the celldivided can be stored. The sound pressure of the background noise can bestored each time the robot moves and the stored results are collectedand calculated so as to be stored as sound pressure of basic backgroundnoise that may occur in the space.

In particular, when the deviation of the stored noise information isequal to or less than predetermined level, the control unit 250 of therobot 200 determines that the noise in the space is constant and can setnoise information for the cell. Then, the robot moves to the space, andthe level of the background noise, which is a level in the noisemeasurement, can be based on the sound pressure of the noise of thepreviously stored cell.

FIG. 9 shows a process of storing sound pressure of noise generated ineach space obtained during a movement of a robot and using the storedsound pressure according to an embodiment of the present invention.

A control unit 250 collectively stores sound pressure of noisecalculated by a noise sound pressure calculation unit 120 of a volumecontrol module 100 a to a map storage unit 210 as noise information,with respect to position information on the received noise cell in theposition) (S61). A control unit of the robot calculates positioninformation of the map storage unit, that is, the deviation of noiseinformation stored with respect to each cell (S62).

In this process, the noise information can be grouped for each cell andtime to calculate a deviation. After the calculation of the deviation,when the deviation is a predetermined level or less (S63) and the robotmoves to the position, the volume conversion unit 140 of the robot mapsthe volume of the speech output in the cell in response to the averagenoise information on the cell (S64).

On the other hand, when the standard deviation is a predetermined levelor more, the volume of the speech output in the cell is mapped inresponse to the noise information generated at the maximum frequency(S65). If there is a large difference in the sound pressure values ofthe noise, instead of the maximum frequency, it is possible to calculatethe average except a largest value and a smallest value.

When the robot moves to the position, the volume conversion unit 140 ofthe volume control module 100 a maps the volume in response to theaverage value or the maximum frequency value of the stored noiseinformation.

Alternatively, when the difference between the noise information at theposition and the sound pressure of the noise calculated by the noisesound pressure calculation unit 120 is equal to or less than apredetermined level, it may be noise that may generally occur at theposition. The exception processing unit 130 may not instruct theexception processing to the noise sound pressure calculation unit 120.

FIG. 10 shows sound pressure of noise stored in a map storage unitaccording to an embodiment of the present invention. The position (Pos)shows a (x, y) position of each cell of the map storage unit. The sizeof the cell can be variously determined according to the size ormovement speed of the robot.

The values of the sound pressure at the respective positions at a firsttime point (Time 1) to a fifth time point (Time 5) are stored. Deviationshows the deviation of the sound pressure of noise at each position. Thestandard deviation at Pos (1, 1) is 1.2 and the standard deviation atPos (3, 5) is 7.6, and the standard deviation at Pos (7, 2) is 7.28.Therefore, when the robot moves to the position of Pos (1, 1), it ispossible to set the average value of the sound pressure of the noise atthe position to 31 and map the volume in response to the average value.

Alternatively, since Pos (3, 5) has a large deviation, it is possible toselect an median value or a maximum frequency value. Alternatively, theaverage value 33 of the remaining measurement values excluding thelargest value 51 and the smallest value 15 can be set as the soundpressure of the noise at the position, and the volume can be mapped inresponse to the median value, the maximum frequency value, or theaverage value excluding largest/smallest value.

Further, when the difference between the noise information at theposition and the actually measured noise sound pressure is apredetermined level or less, the exception processing unit 130determines it as general background noise and does not instruct thenoise sound pressure calculation unit to perform additional exceptionprocessing.

FIG. 11 is a view of timing at which calculation of sound pressure ismade according to an embodiment of the present invention.

For example, in FIG. 11, a sound outputted through a speaker unit 180,for example, TTS is represented as TTS (SPK) and described; however, itis also applied to an output of various sound files outputted by a robotor a volume control apparatus. A command of the user and ambient noiseare inputted to a microphone unit (MIC) 110.

When ambient noise is continuously inputted to the microphone unit (MIC)(S70), a noise sound pressure calculation unit 120 measures noise andcalculates sound pressure level of the noise (Noise SPL Cal) (S71). Inthis process, a start-up word (keyword) is inputted to a microphone unit110 (S72). The user pronounces a specific command (for example, “airstar”) to the robot and the pronounced command is inputted to themicrophone unit 110 and the keyword is confirmed.

A scenario engine unit 150 notifies an exception processing unit 130that a current state is a KA state as the keyword is inputted (S22 ofFIG. 6) and the exception processing unit 130 instructs the exceptionprocessing to the noise sound pressure calculation unit 120 and nolonger calculates the sound pressure of the noise.

The volume conversion unit 140 calculates volume of TTS speech to beoutputted according to the sound pressure level of the noise calculatedin step S71 (noise inputted to a microphone unit in step S70). A speakerunit (SPK) 180 outputs the guide message with respect to a start-up wordaccording to processing of a speech synthesizing unit 160 and a volumecontrol unit 170.

The speech guidance message outputted in S73 is outputted to the volumemapped to the sound pressure level of the noise calculated in S71 (thenoise inputted to the microphone unit in S70). If loud sound suddenlyoccurs after S71, the loud sound is not reflected to the speech guidanceof S73. Further, in the measurement of the sound pressure level of thenoise in S71, it is possible to exceptionally process the noisetemporarily largely generated.

In S73, when a specific guidance message (“please press the microphonebutton or say it”) is outputted, it is in a state of waiting for speechrecognition. The scenario engine unit 150 notifies that this state is aVR state to the exception processing unit 130 (S22 in FIG. 6), and theexception processing unit 130 instructs the exception processing to thenoise sound pressure calculation unit 120 not to calculate the soundpressure of the noise.

If the user inputs the inquiring matter (“baggage storage”) asexemplified in S74 through speech, the robot process it as the TTS asexemplified in S75 (“go straight and turn left”). When the TTS output iscompleted in a specific unit, the microphone unit MIC continuouslyreceives the ambient noise (S77), and the noise sound pressurecalculation unit 120 measures the noise to calculate the sound pressurelevel of the noise (Noise SPL Cal) (S76). The subsequent steps arerepeated as described above.

In summary, in the scenario shown in FIG. 11, the robot or the volumecontrol apparatus determines the volume of the sound to be outputted byusing the SPL of the noise calculated in S71. In this process, thesuddenly increased noise in S71 may be reflected in the calculation ofthe SPL of the noise at a small rate or may be excluded, as the suddenlyincreased and disappearing noise is a temporary phenomenon and isirrelevant to volume of output sound.

Although all components are described by being included in theembodiment of the present invention are combined to one, or by beingcombined to be operated as one component, the present invention is notnecessarily limited to this embodiment, and all components can beselectively combined to one or more and operated within the purposerange of the present invention. Further, although all of the componentsmay be implemented as an independent apparatus, a part or all of thecomponents may be selectively combined to form a plurality ofapparatuses and a part of the components may be implemented as acomputer program that has a program module to perform a part of all offunctions by a processor, for example. The codes and the code segmentsthat are included in the computer program may be easily deduced by thoseskilled in the art of the present invention. The computer program may bestored in a computer readable medium that a computer can read, and thecomputer program may be read and implemented by the computer so as toimplement the embodiment of the present invention. The storage medium ofthe computer program may include a storage medium including asemiconductor recording element, an optical recording medium, a magneticrecording medium. Further, the computer program that implements theembodiment of the invention includes a program module that istransmitted in real time through an external device. For instance,various units and modules depicted in the figures may be separately orcollectively implemented in hardware (e.g., processor, controller,etc.), software, and combinations thereof.

While the present invention has been mainly described referring to theembodiment of the present invention hereinabove, various modificationsand changes can be made at the level of those skilled in the art.Therefore, unless such a modification and change do not deviate therange of the present invention, it will understand that they areincluded in the scope of the present invention.

What is claimed is:
 1. An apparatus, comprising: a speaker; a microphoneconfigured to receive external noise and speech of a user; a noise soundpressure calculator configured to calculate sound pressure of the noisereceived by the microphone; a processor configured to perform exceptionprocessing of the sound pressure of some or all of the noise using thecalculated sound pressure and one of a speech utterance state, a speechreceiving state, or a temporal length state, of the noise; a volumeconverter configured to map volume of the speech in response to thesound pressure of the noise; a speech synthesizer configured tosynthesize speech guidance into a sound file; and a volume controllerconfigured to control the speaker to output the sound file according tothe mapped volume.
 2. The apparatus of claim 1, further comprising ascenario engine configured to provide the processor with information forthe speech utterance state, the speech receiving state, or the temporallength state, of the noise.
 3. The apparatus of claim 1, wherein theexception processor is further configured to perform the exceptionprocessing based on a minimum unit of an uttered sound, when theapparatus is in the speech utterance state and the output is text tospeech (TTS) output.
 4. The apparatus of claim 1, wherein the exceptionprocessor is further configured to: cause the sound pressure calculatorto not calculate the sound pressure of the noise received at microphone,or cause the sound pressure calculator to reduce the sound pressure ofthe noise by a preset ratio and calculate the reduced sound pressure ofthe noise.
 5. The apparatus of claim 1, wherein the exception processoris further configured to: perform the exception processing while waitingfor speech from a user, when a start-up word from the user is receivedby the microphone.
 6. The apparatus of claim 1, wherein the volumeconverter is further configured to: map the volume of the speech at afirst slope in response to a relative increase in the sound pressure ofthe noise; and map the volume of the uttered speech at a second slope inresponse to a relative decrease in the sound pressure of the noise,wherein an absolute value of the first slope is smaller than an absolutevalue of the second slope.
 7. The apparatus of claim 1, wherein thevolume converter is further configured to: divide a section of the soundpressure of the noise into a first section, a second section, and athird section, wherein the sound pressure of the second section islarger than the sound pressure of the first section, and wherein thesound pressure of the third section is larger than the sound pressure ofthe second section; map the volume to increase to a first slope inresponse to the calculated sound pressure of the noise being includedwithin the first section; map the volume to increase to a second slopein response to the calculated sound pressure of the noise being includedwithin the second section; and map the volume to increase to a thirdslope in response to the calculated sound pressure of the noise beingincluded within the third section, wherein the second slope is largerthan the first slope and the third slope.
 8. A robot, comprising: astorage device configured to store noise information of a space oflocations at which the robot has traveled; a moving unit configured tocause movement of the robot; a controller configured to control themoving unit and functions for the robot; and a volume control apparatuscomprising: a microphone configured to receive external noise and speechof a user; a speaker; a microphone configured to receive external noiseand speech of a user; a noise sound pressure calculator configured tocalculate sound pressure of the noise received by the microphone; aprocessor configured to perform exception processing of the soundpressure of some or all of the noise using the calculated sound pressureand one of a speech utterance state, a speech receiving state, or atemporal length state, of the noise; a volume converter configured tomap volume of the speech in response to the sound pressure of the noise;a speech synthesizer configured to synthesize speech guidance into asound file; and a volume controller configured to control the speaker tooutput the sound file according to the mapped volume.
 9. The robot ofclaim 8, further comprising a scenario engine configured to provide theprocessor with information for the speech utterance state, the speechreceiving state, or the temporal length state, of the noise.
 10. Therobot of claim 8, wherein the exception processor is further configuredto: cause the sound pressure calculator to not calculate the soundpressure of the noise received at microphone, or cause the soundpressure calculator to reduce the sound pressure of the noise by apreset ratio and calculate the reduced sound pressure of the noise. 11.The robot of claim 8, wherein the exception processor is furtherconfigured to: perform the exception processing while waiting for speechfrom a user, when a start-up word from the user is received by themicrophone.
 12. The robot of claim 8, wherein the volume converter isfurther configured to: map the volume of the speech at a first slope inresponse to a relative increase in the sound pressure of the noise; andmap the volume of the uttered speech at a second slope in response to arelative decrease in the sound pressure of the noise, wherein anabsolute value of the first slope is smaller than an absolute value ofthe second slope.
 13. The robot of claim 8, wherein the volume converteris configured to apply a sigmoid function in the calculation of themapping of the volume of the speech in response to the sound pressure ofthe noise.
 14. The robot of claim 8, wherein the controller isconfigured to accumulatively store the sound pressure of the noise asnoise information in the storage device with respect to positioninformation on the received noise; and when a deviation of the noiseinformation is equal to or less than a predetermined level, and therobot moves to a position associated with the position information, thevolume converter maps the volume in response to an average value of thestored noise information.
 15. The robot of claim 14, wherein theexception processor is further configured to not instruct the noisesound pressure calculator to do the exception processing when adifference between the noise information at the position and the noisesound pressure is equal to or less than a predetermined level.
 16. Amethod for controlling volume in an apparatus having a speaker and amicrophone, the method comprising: receiving, at the microphone,external noise and speech of a user; calculating sound pressure of thenoise received by the microphone; performing exception processing of thesound pressure of some or all of the noise using the calculated soundpressure and one of a speech utterance state, a speech receiving state,or a temporal length state, of the noise; mapping volume of the speechin response to the sound pressure of the external noise; synthesizingspeech guidance into a sound file; and outputting the sound file, viathe speaker, according to the mapped volume.
 17. The method of claim 16,further comprising: providing information for the speech utterancestate, the speech receiving state, or the temporal length state, of thenoise.
 18. The method of claim 16, further comprising: not calculatingthe sound pressure of the noise received at microphone, or reducing thesound pressure of the noise by a preset ratio and calculates the reducedsound pressure of the noise.
 19. The method of claim 16, furthercomprising: mapping the volume of the speech at a first slope inresponse to a relative increase in the sound pressure of the noise; andmapping the volume of the uttered speech at a second slope in responseto a relative decrease in the sound pressure of the noise, wherein anabsolute value of the first slope is smaller than an absolute value ofthe second slope.
 20. The method of claim 16, further comprising:dividing a section of the sound pressure of the noise into a firstsection, a second section, and a third section, wherein the soundpressure of the second section is larger than the sound pressure of thefirst section, and wherein the sound pressure of the third section islarger than the sound pressure of the second section; mapping the volumeto increase to a first slope in response to the calculated soundpressure of the noise being included within the first section; mappingthe volume to increase to a second slope in response to the calculatedsound pressure of the noise being included within the second section;and mapping the volume to increase to a third slope in response to thecalculated sound pressure of the noise being included within the thirdsection, wherein the second slope is larger than the first slope and thethird slope.